The invention relates to an information-bearing construction such as a letter, ticket, etc. wherein indicia must remain undetected for effective utilization thereof by the intended recipient. A lottery ticket may serve as a model for such information-bearing members, but it should be obvious that it represents but one of many applications for such a construction. For example, such articles have substantial utility in the mailing of credit cards, the transferral of such military information as code keys, the transferral of confidential business information and the like.
Another model would be a package, or pouch, for holding lottery tickets, credit cards, or like articles to be secured.
The problems associated with distribution of lottery tickets serve to illustrate the problems associated with the secret distribution of any readable information. Modern technology gives the unauthorized person a wide number of techniques with which he may attempt an unauthorized reading of information.
Among techniques that may be employed is the use of radiation including the use of X-rays, candling, fiber optics, lasers, infra red and microscopy or any combinations of these. Micro-surgical techniques, perhaps followed by reglueing, are available. Other techniques include using chemicals or thermal effects to read the information. All of these techniques must be guarded against. The possible gains to a third party are high enough to justify a considerable investment in time and money to screen a construction for any vulnerability to detection using any of the foresaid methods. Absolute protection is desirable, but constructions which can be "solved" by techniques taking more than 10 to 15 minutes are also useful in some procedures wherein the information from a large number of articles is being screened rather than obtained for its intrinsic value.
Present techniques for protecting such information are weak. Mere scratch coatings are used over the indicia. In some applications, invisible magnetic recording is utilized. Other procedures known in the art include use of luminescent spot codes readable under ultra-violet light (U.S. Pat. No. 3,464,841); a procedure for destroying a personal photograph on a credit card if the card is tampered with (U.S. Pat. No. 3,679,449); and intermixing of chemicals to destroy an identification serial number on tampering with the card (U.S. Pat. No. 3,707,300). None of these techniques is directed to solving the problem to which applicants have directed their efforts.